In vitro and in vivo laboratory studies indicate that amphotericin may enhance the cell uptake and cytotoxicity of some antitumor antibiotics. Treatment of ten patients (two with breast cancer refractory to Adriamycin and eight with previously untreated sarcomas) revealed no augmentation of the therapeutic index of Adriamycin. In vivo and in vitro studies with combinations of amphotericin and Adriamycin or amphotericin and daunorubicin also showed no enhancement of antileukemic activity against either the L1210 mouse leukemia, P388 mouse leukemia, or P388 mouse leukemia resistant to anthracyclines. This study has therefore been discontinued.